Maintenance and Tech,Piston Slap
Sajeev Mehta
28 July 2024
Hagerty Community member HelenC writes:
Sajeev, my question is how do you disable the stop/start feature on a Jeep Grand Cherokee? It would be a tremendous service to your readers if you explained how to do it on not only Jeep products but GM and Ford.
I know the car companies have not come up with such an iterative feature since they put those seat belt starter interlocks on cars back in 1974. However it was easy to disable by just cutting all the wires under the seat. This aggravation may be more complicated to find which wires to cut so all your help would be appreciated.
Sajeev answers:
Turns out I got this one wrong, as there are modules that defeat this system. But remember these can void your vehicle’s warranty, so let the buyer beware.
Before I reply, please permit me to weasel out of a proper answer. Because getting a representative vehicle from all manufacturers, performing the task (either manually or electronically) to verify for myself, and then subsequently getting banned from all media fleets would kinda tank (what’s left of) my career as an automotive journalist. I’m only kinda joking, as doing this on not-media fleet vehicles would also be too cost prohibitive. And with that out of the way…
Let me instead point you in the right direction to disable auto start/stop in your vehicle. And this “pointing” is more valuable over time, as vehicle systems change over time, but the people who work on them generally do not.
- Call or email ECU tuners (Ford, GM, Chrysler) to see if they can remove auto start/stop from their software. This is often possible, but only they will know as they have access to the software and the ability to do what you want.
- Ask a dealership’s service department if start/stop can be removed either with their software, or unplugging/bypassing a wiring harness. (I assume the answer will be no, but it never hurts to ask.)
- Find out who makes the start/stop starter unit in your application. (Denso is a well known brand in this space.) Once you know the brand you can see what inputs it takes from the rest of the car to operate. Maybe you can disable start/stop without destroying the rest of the starter.
My advice tries to cover all bases, but honestly, you only need the first option. An ECU tuner will know more than anyone else, as modern cars use multiplex wiring that ensures any physical modification will take out more things than just the start/stop feature.
I suspect a tuner can make the system default to “off” so you can hit the button and turn it on if you tire of getting 0 MPG in traffic. Problem is, the tuner’s work isn’t free. It will cost hundreds of dollars, but it’s worth it if you also load a tune that allows for more power (premium fuel sometimes required), eliminate the throttle/torque management software, and firm up the transmission shifts.
Almost all of my EFI-powered vehicles have been tuned by a professional in the aftermarket, and I recommend it for more reasons than just disabling a start/stop feature. But that should get you exactly what you need, no matter what make or model we are discussing.
(For the record, I have no problem with this feature in late model vehicles. Times have changed, its operation is relatively seamless, and eliminating periods of 0 MPG when stuck in suburban sprawl has financial and ecological merit.)
Have a question you’d like answered on Piston Slap? Send your queries topistonslap@hagerty.com—give us as much detail as possible so we can help! Keep in mind this is a weekly column, so if you need an expedited answer, please tell me in your email.
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Read nextUp next:Trying to Get My Armada’s A/C System through the Summer (Part I)
I’m a little disappointed in this article Sajeev, seems a little phoned in, which is not something I expect from you.
While I love auto stop-start when it is on a Hybrid who uses an always engaged brushless motor to do the chore I hate hearing the clash and whine of the auto stop-start systems found on ICE only vehicles when I’m next to one in traffic. Apparently many owners don’t like it either. So much so that even the button included on some models that must be pushed every time the vehicle is turned on isn’t a good enough solution.
Some start-stop systems are turned on or off in code since there are jurisdictions outside of the US that don’t give CAFE credits for start-stop systems. So the aftermarket to the rescue.
Depending on the application they have programmers that change that code, or an electronic module that plugs into either the button to automatically “press” it on start up or some other thing that makes the vehicle sense that start-stop shouldn’t be active and then fool the computer into thinking it is always operating in a condition where start-stop is not indicated.
One of those companies though surely not the only is 4D tech. Here is the Jeep page, the OP didn’t give the year of her Jeep but some are available and I expect newer models will eventually be added as they figure out the trick for that particular vehicle. https://www.4dtech.com/start-stop/jeep/
What really surprises me is that a Fordiphile like you Sajeev aren’t familar with 4D tech as they got their start providing factory upgrade kits for Ford products before getting into feature changer programmers.
For Fords there are lots of things baked into the computers that are turned on, off or adjusted with 2 digits in a line of code or two. That is what allows them to produce the programmer that plugs into the OBD II port and turn features on or off just like the dealer can do with the factory scan tool.
The problem is that those programmers just do one feature. Now if you get the desktop version of ForScan which anyone who owns an OBD-II Ford should have, along with the phone app, you can turn all those features on and off at will.
You just need to find the appropriate cheat sheet for your application, though in many cases the line numbers and digits to change are universal.
Here is the one I’ve referenced to change the temp of the heated steering wheel in my MKZ but it can also be used, among other things, to make the infotainment splash page show a Mustang, Raptor, or other vehicle since all of the vehicles use the same software and all of the options are all baked into the unit and only become active based on the initial programming once they know what vehicle that particular module is scheduled to reside in.
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After reading everyone’s comments, I am pretty disappointed with myself too. I should have found all the modules sold online that solve the problem, and considered all the feature change programs you have highlighted. Well, that is why this weekly column (i.e. with deadlines) has a comments section: to set the record straight.
And thank you for your efforts in that.
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https://www.autostopeliminator.com/ You can get this device for very little money that takes care of your issues with Auto Stop!
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I purchased this product (Autostopeliminator) a few years ago for my 2020 Chevrolet Equinox and returned it immediately. The module does defeat the Auto Stop system; however, it also deactivates the torque converter lock-up feature as well. Difference between lock-up engagement and bypass on the Equinox is 300-400 RPM at 70MPH–That’s a lot of R’s!! Essentially, prematurely wearing out all spinning parts and sucking down more fuel. I can achieve the same function that Autostop provides by shifting the trans to Manual; it deactivates Auto Stop and unfortunately, converter lock-up. If you are in the market for a used Equinox, don’t buy a 2020, I believe it’s the only year they took out the override button.
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Vivre les ordinateurs autel
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Get a BMW, simple switch at start button shuts it off
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Not just BMW
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I like the stop start feature. It is so much easier than to turn of the car and then put he car in Neutral and then manually restart. I do not understand how people prefer to do this instead of using the automatic stop start system. Unfortunately my SUV does not have the stop start feature. So is there an easy way to put the stop start feature in your car
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Thank you for your expository comment, Sajeev. If we want to continue having access to ICE cars, we need to find ways to make them less polluting. Personally I find start/stop much less annoying than the 55mph national speed limit or arbitrary congestion fees.
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I have no vehicles with auto/start/stop, but I do have one (rather personal and minor) reason to want to disable it if I had it. I’m in a decades old habit of glancing at my tachometer not only while in motion, but when stopped (idling, when either in Drive or Neutral). I do this in the same manner as looking at oil pressure, temp, and other gauges. I like to know what is happening with my engine at all times, and monitoring the information that’s there in the instrument cluster is important to me. I can tell a lot about a potential misfire, runaway or stuck throttle – well, you get the picture. The engine shutting down while motion is stopped would panic me. Sure, I could re-learn my habits, but I’d be missing out on – what to me – is a critical time to be looking at engine health.
Now, on the other hand, I get the argument for reducing 0 MPG emissions, and I suppose if I was doing stop-and-go commutes on those famously wicked Houston Freeways* I’d see more potentiality, but I just can’t really frame in my mind that when I drive into town and hit a store or two that the few 30-second-or-less instances of “engine off” I’d experience would make much of a dent, especially since there will inevitably be a guy next to me at the stoplight in the jacked up F-250 Powerstroke who will delight in dousing me with a cloud of black exhaust larger than my house when the light turns green.
Oh, I get it – “every little bit helps”, but I also believe that if the powers that be are going to dictate that my personal vehicle makes a 1/zillionth % reduction in emissions at every stop sign, they’d better show me that they are also dictating (and enforcing) to EVERYONE out there in a commensurate manner.
*(or MANY other areas in the world, but Sajeev has planted a fearsome image in my brain with a photo I just can’t unsee)
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The biggest problem I have with it is that the A/C shuts off too. & in Florida that’s an issue for most of the year. I also agreed with all the reasons that you mention DUB6. Cheers!
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My personal favorite comment yet on the start /stop issue. “The cloud of smoke from the powerstroke F-250 really does happen and that real stuff to laugh about
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You do not give the year or model Jeep.
Most are able to hit the start button and disable the engine stop. You may want to review your owners manual.
Also there are several simple tuners that plug into the OBD2 port that disables it.
There are some under hood hacks but I would avoid them .
Few vehivcle do not have a defeat button.
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The worst thing on ANY internal combustion engine is dry start, period. This is all rummed up by the fake doomsday promotion people, & the auto manufacturers to wear your vehicles parts out sooner. Stupidest thing ever. The air is fine, earth heals itself just like our bodies do.
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Until they don’t.
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I agree with this wearing parts out sooner because my son had a 2022 Ram pickup that had this feature. At 36,680 miles on it the starter went out on it, stranding him at a stop light in a rather large city. Cost him almost $300 to have the starter replaced as it was over the 3/36 warranty. Even though it was only 680 miles over, Chrysler wouldn’t do anything for him. After it was fixed, he sold it and got an 07 Suburban that doesn’t have it. Suburban now has almost 300,000 miles on it and runs like a top.
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Caught up in manufacturers getting away with E.P.A. SCAMS AT THE VERY LEAST C current automotive warranties should be five years WITH Un limited mileage if serviced by the dealer .The fact is GOOD SERVICE IS HARD TO GET
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That was on the dealer, not Stellantis. They give dealers a 12 month/12,000 mile goodwill policy for things like this. I know this because I was a dealer.
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My wife’s Jeep Wrangler V-6 took a new starter at 49k. Starters do 150k starts in 1/3 the time/miles.
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You can’t be serious about air pollution– It is a big problem—Nobody that is Honest can deny that-
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No one likes air pollution except maybe farmers in arid areas. However, from my perspective, it seems like we’re focused on a leaky faucet during a monsoon. Additionally, it seems our focus on air pollution has increased our acceptance of land and water pollution. It’s kind of like the person feeling good about putting their plastic bottle in the recycle bin but not realizing it’s shipped to Malaysia to be burned. (nothing in this comment is proven fact and is just the opinion of the author)
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Well, our bodies heal themselves by killing off the critter that’s doing the damage to them, either by using the immune system or by medicine. If the earth works the same way, it does not augur well for the long-term existence of mankind.
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My 2017 Ford F150 has a builtin bypass to eliminate the stop start function through the steering wheel control panel.
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I drive a Honda Civic and easiest way I’ve found is to leave the air conditioner on Hi or Lo but turn fan speed all the way down. It will not activate due to compressor another way is to let off brake once you’ve stopped but not all the way just enough to remain stopped there’s a sweet spot in there
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As a transmission rebuilder I can tell you that the start/stop feature is horrible for your transmission especially in gm front wheel drives.. every time we get one of of these in we ask the customer if they are using the start/stop feature and in better than 75 percent of the time the answer is yes..
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Twice I’ve attempted to go into reverse unfortunately right when the engine decided to shut itself off because I sensibly had my foot on the brake pedal prior to shifting. This messed up the trans function in the Terrain for the rest of the drive. Both times it was okay after sitting. A common situation for this to occur is when one has to back into an open filling station stall, or when getting the mail–any situation where one goes from forward to reverse once the engine is warmed.
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Or just drive the darn thing. You get used to itvwas lesrn the tricks yo keep it running.
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“itvwas lesrn the tricks yo”
Shoot, I was gonna say that, but you beat me to it! 😉
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Autostop Eliminator
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Best $100 I ever spent will save me thousands in repair bill in the future
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I would have gladly paid the Benjamin for that AS/S Eliminator for my 2024 Subaru. Fortunately, I found a different solution on Amazon for about half that price. It is a replacement for the AS/S button on the dashboard, and like the Eliminator causes the system to remain in the condition it was in when you shut down your vehicle (if AS/S was “on”, it starts back up as “on”; if it was “off” it starts back up as “off”).
Perhaps, “on paper” the AS/S system increase the fuel economy, but my own experience is that the fuel savings are trivial at best, and probably outweighed by the additional cost of a heavier-duty battery and the extra wear and tear of frequent engine starts.
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I drove my son’s new genesis the other day and it had that stop start Garbage on it. I stopped at the stop sign and let off the break. It felt like somebody bumped into the back of my car. I learned it all you have to do is hold the pedal partway and it won’t shut off another useless thing on the car.
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I also purchased the Auto Stop Eliminator for my 2023 Hyundai Palisade and is the best! It only took 5 minutes to install and have had no issues!
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I’m on the fence on the start/stop feature
I wonder what the numbers are for real gas savings… particularly for primarily rural drivers like myself.
My fleet is a bit too old to be adorned with this feature (1965-2012), but I rented an Audi the other day which was a pretty snappy responsive car. I noted however that it bogged a little bit getting out of the light, and I realized it was the start/stop as the car had to start… then go. I turned it off with the button on the dash and the car started accelerating from a stop the way I expected it to
Most cars have a disable button on the dash, but it resets to on as soon as you cycle the key
If the tune trick doesn’t work, there may be limited options. I suspect in most cars these days, the start command from the key goes to an ECU, then the ECU triggers the starter relay. In this arrangement, there is only one wire from the ECU to the starter relay commanding a start, so snipping a wire is probably not an option. The only alternative in this case would be to go ahead and snip the wire, then install a start pushbutton in the car somewhere. I suspect this approach might be a little to redneck for most folks
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It really saves little but it is a government loophole for automakers to raise the CAFE and Emissions rating of their engines. Other off cycle credits like solar glass and pain are also being used.
Automakers are desperate to sell you whst you want but EPA and CARB regulations are making it tougher. This is why VW and Toyota got caught cheating on emissions.
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Up to 7% were the tested numbers I’d seen, based on the normal CAFE mix. If your driving doesn’t have many traffic lights, you won’t notice a difference. The smaller percentage would probably be within the normal variation you see in mileage from tank to tank.
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Wont the starter itself burn out after all that on and off ??
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No, they are heavy duty versions intended for the extra cycles. That info is straight from the owners manual of my vehicle, not just something I made up. 🙂
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“It’s designed for that!”
I’m sure it’s true!
Right?
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I recall whichever company tested the design to 500k starts
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No, I checked and found out that Dodge uses a heavy duty starter to take care of the start/stop vehicles.
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They have a separate battery for the stop start my buddy just had a replace one in his car cost them almost $250 for the battery
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My complaint is why didn’t factory just give the driver the choice. On if you want it and off if you don’t. Your ac doesn’t come on unless you turn it on. Imo it operates backwards
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Off cycle mileage credits are why we have them. These are credits that permit larger engines with more power that many want. Some cases they can offer the defeat button some not.
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I bet you can just go to settings and disable
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Nope. I have a 22 JGC… No setting.
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As an FYI, I am aware of a odbii module that would effectively disable the start/stop feature on our 2015 volvo s60. I believe it electronically “pushes” the button we have on our dash. The cost was high, but i don’t recall exact number. Perhaps price has come down? Also, I don’t mind the feature, but my wife HATES it!
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Most of them I’ve encountered don’t operate unless the drivers seatbelt is fastened. Not saying to drive around unbelted, but there’s this two-wire switch looking for a binary signal…
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I was told the computer counts the number of times it restarts and when it reaches the magic number of starts it turns on the check engine light and the code says replace the starter.
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Not true.
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Toyota, Mr Knows Everything
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Very unnerving for those of us who drove carburetor cars back in the day and had to goose the gas pedal on cold mornings. You had some close calls pulling out into a busy street to make your holeshot. My Subaru simulates that. Absolutely detest it.
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Just wait until the auxiliary battery goes bad or unplug it ..jeep runs a auxiliary battery for that system
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Yes my wife’s Pacifica we had to replace the battery for
$250
For something we shut off immediately
Gummint at work
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If either battery goes bad, replace both batteries.
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